The data was thoroughly researched using the Times Index-Gazetteer of the World, the Times Atlas of the World, and the National Atlas of the United States of America to ensure correct spelling and location of named features. The spelling and major geographical features applied to smaller features (minor) such as cities, towns, mountain peaks, etc., are in accordance with these publications. It is understood that some political boundaries and names of countries are subject to change. The data was written on NASA keypunch transmittal sheets and punched into data cards. These data cards were then machine sorted alphabetically by major feature and minor feature.